When I play my singleplayer room I have a large room in the sky. When I logged of and then back on the room became bright instead of dark ( There is no light source). I just want to know if monsters will still spawn in that room as it is supposed to be dark.

*What I expected to happen was that the room would stay dark.

*What actually happened was the room became light with no light source.

Steps to Reproduce:
1. Make a large dark enclosed room in the sky.
2. Close your Minecraft
3. Go back into the room and it should be light